As is known in the art, the city water system comprises water taps attached to individual terminal channels to allow a controlled amount of water to be discharged through the spout by turning on said tap. Users of such city water system often tend to turn on taps to a large extent to discharge a large wasteful amount of water even when they actually use a small amount of water. With the object of preventing wasteful discharge in connection with the utilization of such city water system, there have heretofore been developed water saving valves intended to limit the amount of discharge water by utilizing the fluid pressure as the flow rate increases due to the increasing degree of the opening of the tap.
As an example of conventional water saving valve, there is known a water saving valve for use in flow rate adjusting cocks developed by the same applicant and disclosed in Japanese Laid-Open Utility Model Publication No. 41,283 of 1991. This water saving valve for use in flow rate adjusting cocks disclosed in Japanese Laid-open Utility Model Publication No. 41,283 of 1991 is designed such that when the tap has been closed, the spherical valve body is abutting against a stop member under the action of the valve body urging means to shut the fluid channel, and when the tap is gradually turned on until the flow rate on the inlet side is W.sub.1, the spherical valve body is axially moved against the urging force of valve body urging means until it reaches an intermediate position which lies away from the stop member and which maintains a channel between the stop member and a conical shaped valve seat surface, allowing the fluid to be discharged at the flow rate w.sub.1 from a fluid outlet opening through the channel between the stop member and the conical-shaped valve seat surface, and on the other hand when the flow rate on the inlet side increases to W.sub.2, the resulting fluid pressure forces said spherical valve body to abut against the conical-shaped valve seat surface against the urging force of the valve body urging means and thereby close the fluid outlet opening, thus shutting off the discharge of the fluid. That is, according to the one disclosed in Japanese Laid-Open Utility Model Publication No. 41,283 of 1991, it is arranged that the outflow of the fluid is shut off at the stage when the flow rate on the inlet side reaches W.sub.2 ; in this point the arrangement has an inconvenient side to it.
As for another example of a conventional water saving valve, there is known a flow rate adjusting water saving valve developed by the same applicant and disclosed in Japanese Laid-Open utility Model Publication No. 19,743 of 1993. This flow rate adjusting water saving valve disclosed in Japanese Laid-Open Utility Model Publication No. 19,743 of 1993 is designed such that when the tap has been closed, the spherical valve body is abutting against a stop member under the action of the urging means to shut, the fluid channel, and when the tap is gradually turned on until the flow rate on the inlet side is W.sub.1, the spherical valve body is axially moved against the urging force of valve body urging means until it reaches an intermediate position which lies away from the stop member and which maintains a channel between the stop member and a conical-shaped valve seat surface, allowing the fluid to be discharged at the flow rate w.sub.1 from a fluid outlet opening and from a fluid radial outflow opening through the channel between the stop member and the conical-shaped valve seat surface, and on the other hand when the flow rate on the inlet side increases to W.sub.2, the resulting fluid pressure forces said spherical valve body to abut against the conical shaped valve seat surface against the urging force of the valve body urging means and thereby close the fluid outlet opening, but allowing the fluid to be discharged from the fluid radial outflow opening. This example of conventional water saving valve has not been adapted to fully function in the matter of the regularity of flow of the fluid. Further, this arrangement requires a valve body urging means comprising a coil spring or the like, thus having the problems that the number of parts is large and that the construction is complicated.
Further, a conventional water saving valve has been provided which is designed such that the fluid outlet opening is simply reduced in diameter (for example, a small hole of about I mm in diameter) as compared with the fluid inlet opening in the main valve body, in order to increase the flow rate by reducing the amount of water simply to achieve the saving of water. This conventional water saving valve having such fluid outlet opening of small diameter has the serious problem of the fluid outlet opening being choked, requiring regular cleaning in order to secure the passage through the fluid outlet opening.
Accordingly, this invention relates to improvements in a constant flowrate water saving valve effectively applied in a fluid channel containing a flow rate adjusting cock, such as a tap, particularly extremely effectively applied to a fluid discharge part, such as a shower head, the arrangement being such that a suitable amount of water is discharged in a state of regular flow which gives a feeling of affluent flow under water saving conditions even when the tap is operated in the direction of maximum degree of opening and such that the fluid is discharged through the shower in a state in which air is sucked and mixed therein during the discharge of the fluid.